My dream reveal would go like this.
The sound of a single trumpet playing a relatively high pitched Do.
Daaaaaaaa-da da da dada daaaaaaa
[Camera scrolls through Green fields]
(Now a trumpet chorus plays lower pitched Mi)
Duuuuuuuuuuuuuuuuun
[Super Smash Bros logo appears in white Background]
Again
Do
Daaaaaaaa-da da da dada daaaaaaa
[Camera pans through blue skies with birds flying together]
(Now lower pitched Mi)
Duuuuuuuuuuuuuuuuun
["X" appears in white Background]
Solo trumpet goes:
Do, dodo re, rere do, with build up (gave up here)
Slimes pop out of the bushes
[Dragon Quest logo appears in white Background]
A slashing silouette comes out of nowhere splitting the slimes in half.
Camera pans up. It's Erdrick sheathing back his sword on his back.
"Erdrick draws near"
*Footage of basic neutral combos on Link.
*Footage of Erdrick's aerials using different weapons on Shulk.
*Footage of Erdrick's magic attack system and MP useage on Ness.
*Erdrick and Cloud fighting back to back against FE characters.
Then Ryu and Megaman land to their left.
Sonic and Bayonetta to their right.
*Erdrick beating DQ enemies in adventure mode.
*Slime hopping on Erdrick's head as a taunt.
*Erdrick showing off Chimera Wing for recovery move (works like a non-explosive Warp Star)
*Alt colors are protagonists from other DQ games.
*Erdrick uses final smash Whistle, where every monster from the DQ series stampedes over the enemy, led by slime.
*Super Smash Bros logo appears again.
*Erdrick walking in a forest, when Magic Marionettes appear. He rushes to slice them, when he notices one is left in the shadows.
Before he lands a slash, the ahadowy marionette dodge's out of the way.
Geno gives it a whirl.
*Footage of Geno in action
*Smash Bros logo X Dragon Quest appear, and then "X Super Mario RPG" logo is added.
Well, that's my dreamed final reveal.